Thinking in Patterns chapter 17: Multiple languages

Thinking in Patterns with Java V0.9: chapter 17: Multiple languages: TIPatterns.htm#_Toc41169757

1, Sections:

Multiple languages  120

  Interpreter motivation. 121

  Python overview.. 122

    Built-in containers. 123

    Functions. 124

    Strings. 125

    Classes. 127

  Creating a language. 130

  Controlling the interpreter. 134

    Putting data in. 134

    Getting data out. 140

    Multiple interpreters. 143

  Controlling Java from Jython  144

    Inner Classes. 148

  Using Java libraries. 148

    Inheriting from Java library classes  150

  Creating Java classes with Jython  151

    Building the Java classes from the Python code  156

  The Java-Python Extension (JPE)  157

  Summary. 157

  Exercises

2, The main content and feeling:

  First at all, let me remember a fact, this book is written at 3 years ago,

too many changes has been taken, so I think the language Python introduced

by Bruce in this book has many changes. And, there are many kinds of other languages maybe has present.

  Then, let us see what has been told in this chapter.

  At last, two days' reading without installing Python or Jython, I get a

conclusion: Python, maybe is the best lovely program language of Bruce's. The

most part of this chapter is introducing Python. On the other hand, the Interpreter Pattern in this Design patterns book is a little part of this chapter.

 

  What is Interpreter Pattern?

  It says:

 

Sometimes the end users of your application (rather than the programmers of that application) need complete flexibility in the way that they configure some aspect of the program. That is, they need to do some kind of simple programming. The interpreter pattern provides this flexibility by adding a language interpreter.

  Note, although in almost all applications there are some factors that end

user can change it by some ways, for example, input something or press some

buttons, etc.. But, in a interpreter pattern, it provides end users the most probability for custom there many factors by simple programming.

  And, a ready for use this kind of Interpreter system introduced by Bruce is

Jython, a pure Java implementation of Python language. Of course, you can

write your own Interpreter sytem. But it seems too unecessary.

  Along with Bruce's lines, I got some about Python and Jython, and this is

almost real the first touch of this language for me. I can understand little

 bit of examples in this book without to run it under *ython.

  Use some sentences in this book to summary the understanding for *ython of

mine.

 

Python is a language that is very easy to learn, very logical to read and write, supports functions and objects, has a large set of available libraries, and runs on virtually every platform.

 

It is marvelous for scripting, and you may find yourself replacing all your batch files, shell scripts, and simple programs with Python scripts. But it is far more than a scripting language.

 ...

 If you program with *ython, no redundant charactor typing. And it can be

worked together with java very well. All the Jython class and Java class can

almost interact without any problem. And, if you need native Python program

interact with Java, a resolution called The Java-Python Extension (JPE) can be

used.

  In this book, Bruce says maybe a new Design Pattern called Multiple Language

can be invented. In this way, mixing languages to resolve a question can be

better than using only one language. All the languages has its advantage and

shortage, mix them is a good idea.

  Bruce says:

 

To me, Python and Java present a very potent combination for program development because of Java?s architecture and tool set, and Python?s extremely rapid development (generally considered to be 5-10 times faster than C++ or Java).

  But, I doubt that "5-10 times faster than C++ or Java", although I am not a

professional programmer(I don't work in IT), I think it is impossible that a

language has 5-10 times development speed than others. Because, building an

application need not only coding, but also many other works. I suppose, Python is good at coding, at building a good classes system, but, what classes are we need? How do they interact with each other? etc.. These kind of things is can't be reduced many only by a language.

 But, maybe, "Python?s extremely rapid development" is only refer to coding,

and mix this coding process with "Java's architecture" which is good at

building system architecture.

3, Questions about programming:

  1), if you create fields using the C++/Java style, they implicitly become static fields.

  2),

In addition, Jython’s JavaBean awareness means that a call to any method with a name that begins with “set” can be replaced with an assignment, as you can see above.

You are not required to inherit from Object; any other Java class will do.

Note that it?s important that the directory where the target lives be specified, so that the makefile will create the Java program with the minimum necessary amount of rebuilding.

4, Questions about english language:

1), Strange words:

 advantageous, arbitrarily, stuck, tedious, Interpreter, distraction, for-profit, royalties, basically, incorporating, scales up, purity, referred to, marvelous, affirmative, subsequent, add-on, acknowledged, associative, formalize, takes on, imitate, verbiage, signature, other than, tuple, control over, decimal place, spare, set off,  turns out to be,  aggressively, albeit, penchant, comma, from within, deceptively, thorough, further down, ambiguous, back and forth, it is worth noting that, disposal, endearing, intuitively, awareness, automated, shorthand, presumably,

come over, lambda, succinct, hood, frustrating, stem from, arguably, lurking,

potent, flesh out, terrific, leverage

2), Strange sentences:

 Indenting can nest to any level, just like curly braces in C++ or Java, but unlike those languages there is no option (and no argument) about where the braces are placed  the compiler forces everyone’s code to be formatted the same way, which is one of the main reasons for Python’s consistent readability.

 Note that Python was not named after the snake, but rather the Monty Python comedy troupe, and so examples are virtually required to include Python-esque references.

   incomplete